1. Field of the Invention
The present invention generally relates to an antenna device, in particular, to a slot antenna device.
2. Description of Related Art
As the development of wireless charging technology, there have been increasing numbers of portable electronic devices disposed with charging antennae to receive charging signals via a wireless transmission manner, so that the portable electronic devices have a function of wireless charging. Specifically, most of the current charging antennae are designed by adopting a slot antenna structure. However, general slot antenna structures are usually designed to be single-slot structures, so as to emit a single frequency band correspondingly. Therefore, if the slot antennae could be operated at multiple charging frequency bands, a multiple-slots structure has to be designed to emit the other frequency bands, thus designing the slot antenna structures that are capable of being operated at multiple frequency bands becomes complicate. Therefore, designing slot antenna devices that are capable of being operated at multiple frequency bands without having complex slot structures is an important issue at present, so as to reduce a cost of designing and manufacturing the wireless charging devices. Accordingly, several embodiments of the present invention as solutions are provided as follows.